Mahle Pistons & Engine Parts

The best Mahle parts in this collection are its MS forged piston sets for Subaru EJ engines, including a 100mm bore, 79mm stroke, 8.5:1 set listed for the 2004-2021 WRX STI and an EJ20 set with a 92.50mm bore, plus Clevite bearings and a head gasket set for Subaru 2.5L EJ255 and EJ257 engines. Match bore, stroke, pin size, and compression ratio to your block before you buy, and check your engine code carefully.

Forged pistons replace the factory cast pistons during a rebuild, and the numbers in each listing are the build sheet: bore, stroke, rod length, pin diameter, dish volume, and compression ratio must suit your block, rods, and gasket. Bearings are the other half of a careful rebuild. The Clevite standard main and rod bearing sets listed here cover Subaru EJ models across WRX, STI, and Legacy years, and a complete head gasket set seals the heads when the engine goes back together.

Mahle is the headline brand here, represented by its MS forged piston sets for the Subaru EJ family. One set is listed for the 2004-2021 WRX STI at 100mm bore and 8.5:1 compression, and another covers the 2.2L EJ20 at 92.50mm bore and 8.1 compression, giving builders two clearly specified options rather than a generic piston. Through these products Mahle serves the measured rebuild: pistons sold with full dimensions in the title so a builder can confirm the combination on paper first.

Clevite appears throughout as the bearing and gasket name, with main sets for WRX and STI 2002 and newer and Legacy 1990-2010, rod pairs for EJ models, and the head gasket set for the 2.5L EJ255 and EJ257. Builders comparing piston brands can also look at JE Pistons, known for forged racing pistons across many import engines, and CP Pistons, whose kits are a common choice for turbo Subaru builds. Wiseco is a third long-running forged piston option worth comparing on bore and compression before you commit.

Start with the Mahle MS forged piston set for the WRX STI or the EJ20 piston set with its full dimensions listed, then pair them with the right connecting rods and performance crankshafts for the rest of the rotating assembly. For context on a modern Subaru build, read our 2015 FA engine WRX product highlight.

Are forged pistons a direct replacement for stock pistons?

Only when the bore, stroke, pin, and compression figures match your build. These sets list those dimensions in their titles, and a machine shop should confirm clearances during the rebuild rather than treating them as a simple drop-in swap.

Which bearings should I replace during a rebuild?

Main and connecting rod bearings are normally replaced together when an EJ engine is apart. The Clevite sets here are listed as standard size, so confirm your crankshaft has not been machined to an undersize before ordering.

Do I need a tune after fitting forged pistons?

A same-compression piston set is a strength upgrade, but any change to compression, bore, or supporting parts should be discussed with your tuner beforehand.

What else should I buy with pistons?

Plan on bearings, a head gasket set, and the rods your builder specifies. Buying the rotating assembly as a matched plan avoids a mismatch with the engine already apart.